Shifting tool and associated methods for operating downhole valves

ABSTRACT

A shifting tool can include a flow restrictor outwardly extendable in a well. A method can include flowing a fluid through a flow restriction, thereby creating a pressure differential and, in response, shifting a closure member while the fluid flows through the flow restriction. Another method can include positioning a shifting tool in a tubular string, then outwardly extending keys from the shifting tool in response to fluid pressure applied to the shifting tool, then engaging the keys with a profile formed in a closure member, and then shifting the closure member between open and closed positions.

BACKGROUND

This disclosure relates generally to equipment utilized and operationsperformed in conjunction with a subterranean well and, in examplesdescribed below, more particularly provides a well system, a bottomholeassembly, a shifting tool and associated methods for operating downholevalves.

A bottomhole assembly can be used to selectively operate multipledownhole valves providing controllable communication with correspondingreservoir zones. In some situations, this selective operation of thedownhole valves enables the respective reservoir zones to beindividually or selectively fractured.

Therefore, it will be readily appreciated that improvements arecontinually needed in the art of designing, constructing and utilizingwell systems, bottomhole assemblies, shifting tools and associatedmethods for operating downhole valves. Such improvements may be usefulin situations where reservoir zones are to be individually orselectively fractured, or in other situations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative partially cross-sectional view of an exampleof a well system and associated method which can embody principles ofthis disclosure.

FIGS. 2A & B are representative partially cross-sectional views ofexample completions that may be used with the FIG. 1 well system.

FIGS. 3A-D are representative cross-sectional views of successive axialsections of an example of a bottomhole assembly that may be used in thewell system and completions of FIGS. 1-2B.

FIGS. 4A & B are representative cross-sectional views of successiveaxial sections of an example of an unloader valve section of a packerassembly that may be used in the bottomhole assembly of FIGS. 3A-D.

FIGS. 5A-C are representative cross-sectional views of examples ofrespective packer, anchor and setting control sections of the packerassembly.

FIGS. 6A-C are representative cross-sectional views of successive axialsections of an example of a shifting tool that may be used in thebottomhole assembly.

FIG. 7 is a representative cross-sectional view of an example of adownhole valve that may be used in the well system and completions ofFIGS. 1-2B.

FIG. 8 is a representative cross-sectional view of the well system, inwhich the bottomhole assembly is being positioned in a tubular string.

FIGS. 9A-C are representative cross-sectional views of successive axialsections of the well system, in which the packer assembly is set in thetubular string.

FIGS. 10 is a representative cross-sectional view of a section of thewell system, in which the unloader valve is opened.

FIGS. 11A & B are representative cross-sectional views of successiveaxial sections of the well system, in which a bypass valve of theshifting tool is opened.

FIGS. 12A-C are representative cross-sectional views of successive axialsections of the well system, in which the packer assembly is unset.

FIGS. 13A & B are representative cross-sectional views of successiveaxial sections of the well system, in which keys of the shifting toolare engaged with a profile in the downhole valve and an annular flowrestrictor of the shifting tool is actuated.

FIG. 14 is a representative cross-sectional view of a section of thewell system, in which a sleeve of the downhole valve is displacedsomewhat with the shifting tool.

FIG. 15 is a representative cross-sectional view of a section of thewell system, in which flow across the annular flow restrictor results ina pressure differential across the sleeve.

FIGS. 16A & B are representative cross-sectional views of successiveaxial sections of the well system, in which the downhole valve isopened.

FIGS. 17A-C are representative cross-sectional views of successive axialsections of the well system, in which the packer assembly is set.

FIG. 18 is a representative cross-sectional view of a section of thewell system, in which the unloader valve is opened prior to unsettingthe packer assembly.

FIG. 19 is a representative cross-sectional view of a section of thewell system, in which the shifting tool keys are engaged with a profilein the sleeve.

FIG. 20 is a representative cross-sectional view of a section of thewell system, in which the sleeve is shifted to a closed position.

FIG. 21 is a representative cross-sectional view of a section of thewell system, in which the bottom hole assembly is positioned foroperating another downhole valve.

FIG. 22 is a representative flow chart for an example of a method foroperating one or more downhole valves.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a system 10 for use with asubterranean well, and an associated method, which can embody principlesof this disclosure. However, it should be clearly understood that thesystem 10 and method are merely one example of an application of theprinciples of this disclosure in practice, and a wide variety of otherexamples are possible. Therefore, the scope of this disclosure is notlimited at all to the details of the system 10 and method describedherein and/or depicted in the drawings.

In the FIG. 1 example, a tubing string 12 is positioned in a wellbore 14lined with casing 16 and cement 18. In this example, the tubing string12 is of the type known to those skilled in the art as “coiled tubing,”since the tubing is typically stored on a reel or spool 20 and issubstantially continuous. The tubing string 12 is conveyed into thewellbore 14 via an injector 22, a blowout preventer stack 24 and awellhead assembly 26.

Note that it is not necessary for the tubing string 12 to comprisecoiled tubing. In other examples, jointed tubing or another type ofconveyance may be used to convey and position a bottomhole assembly (notshown in FIG. 1, see FIGS. 3A-D) in the well. Thus, the scope of thisdisclosure is not limited to any of the specific details of the tubularstring 12 or any other components or elements of the well system 10 asdescribed herein or depicted in the drawings.

When the tubing string 12 is positioned in the well, an annulus 28 isformed radially between the wellbore 14 and the tubing string 12.Fluids, slurries, gels and other types of flowable substances may beflowed into the annulus 28 from surface, such as, using a pump 30connected to the wellhead assembly 26. Similarly, fluids, slurries, gelsand other types of flowable substances may be flowed into the tubingstring 12 from surface, such as, using another pump 32 connected to aproximal end of the tubing string at the spool 20. Fluids and otherflowable substances can also flow from downhole to surface via theannulus 28 and tubing string 12.

Referring additionally now to FIGS. 2A & B, examples of completions thatmay be used with the well system 10 are representatively illustrated.However, it should be understood that the scope of this disclosure isnot limited to completions of the types depicted in FIGS. 2A & B.

In the FIG. 2A example, a tubular string 34 has been positioned in anearth formation 36. The tubular string 34 could comprise a casing (suchas the casing 16 of FIG. 1) or other tubulars known to those skilled inthe art as liner, tubing or pipe. The scope of this disclosure is notlimited to use of any particular type of tubular string.

A series of spaced apart downhole valves 38, 40 a-e are connected in thetubular string 34. Each of the downhole valves 38, 40 a-e provides forselective fluid communication between an interior of the tubular string34 and a respective one of multiple formation zones 36 a-f.

The zones 36 a-f may be individual zones of the same formation 36, orthey may be zones of multiple earth formations. Although a single one ofthe downhole valves 38, 40 a-e is depicted in FIG. 2A as correspondingto a single one of the zones 36 a-f, in other examples multiple valvescould correspond to a single zone, or a single valve could correspond tomultiple zones.

As depicted in FIG. 2A, the zones 36 a-f are isolated from each other atthe tubular string 34 by packers 42 positioned between adjacent zones.However, in other examples, cement or another type of annular barriermay be used to isolate the zones 36 a-f from each other.

In the FIG. 2A example, the downhole valve 38 is pressure actuated. Withthe other downhole valves 40 a-e closed, pressure in the tubular string34 can be increased (such as, using one or both of the pumps 30, 32) toa predetermined level, at which point the valve 38 will open. Suchpressure actuated valves are well known to those skilled in the art, andso are not further described herein.

In some examples, in which the wellbore 14 at the completion ishorizontal or highly deviated, the downhole valve 38 may be of the typeknown to those skilled in the art as a “toe valve,” since it isconnected in the tubular string 34 at or near a “toe” or distal end ofthe tubular string. However, the scope of this disclosure is not limitedto use of the downhole valve 38, or to use of any valve at or near adistal end of the tubular string 34.

As depicted in FIG. 2A, the other downhole valves 40 a-e can be actuatedusing a bottomhole assembly (BHA) 44 connected in the tubing string 12.The BHA 44 is “bottomhole,” in that it is connected at or near a distalor “bottom” end of the tubing string 12. It is not necessary for the BHA44 to be positioned at or near a “bottom” or distal end of the wellbore14.

In the FIG. 2A example, the BHA 44 includes a packer assembly 46 and ashifting tool 48. In other examples, other or different tools, sensors,etc., may be included in the BHA 44, or otherwise connected in thetubing string 12. Thus, the scope of this disclosure is not limited toany particular components (or number or combinations of components) inthe BHA 44.

The packer assembly 46 is used to selectively seal off the annulus 28between the BHA 44 and the wellbore 14. The packer assembly 46 alsoselectively secures the BHA 44 relative to the tubular string 34. Whenthe packer assembly 46 is “set,” the annulus 28 is sealed off at thepacker assembly, and the packer assembly is secured against longitudinaldisplacement relative to the tubular string 34. In this example, thepacker assembly 46 can be repeatedly set and “unset” (flow through theannulus 28 at the packer assembly is again permitted, and the packerassembly can displace longitudinally relative to the tubular string 34)downhole.

A suitable commercially available packer assembly for use in the wellsystem 10 is the REELFRAC™ marketed by Weatherford International, Ltd.of Houston, Tex. USA. In the further description below, operation of thepacker assembly 46 is described as if it is the same as, oroperationally similar to, that of the REELFRAC™. However, the scope ofthis disclosure is not limited to use of any particular packer assembly.

The shifting tool 48 is used to actuate the downhole valves 40 a-ebetween open and closed configurations. The shifting tool 48 canphysically engage each of the downhole valves 40 a-e. In some examples,the shifting tool 48 can include an extendable flow restrictor thatincreases a restriction to flow through the annulus 28 at a selecteddownhole valve 40 a-e, in order to actuate the valve as described morefully below.

In an example method associated with the well system 10 completiondepicted in FIG. 2A, the downhole valves 38, 40 a-e are all initiallyclosed. Pressure in the tubular string 34 is then increased, until thedownhole valve 38 opens. The zone 36 a is fractured by flowing fluids,slurries, gels, acids, spacers, etc., from the wellbore 14, through theopen downhole valve 38 and into the zone 36 a.

The tubing string 12, including the BHA 44, is then conveyed into thetubular string 34. The packer assembly 46 can be set and pressuretested, for example, above the open downhole valve 38 (e.g., in theposition depicted in FIG. 2A).

After pressure testing, the packer assembly 46 can be unset and the BHA44 can be positioned so that the shifting tool 48 engages the downholevalve 40 a. The BHA 44 can then be displaced longitudinally downward (asviewed in FIG. 2A) to shift the downhole valve 40 a to an openconfiguration.

The longitudinally downward displacement of the BHA 44 can be producedby slacking off on the tubing string 12 at surface (so that a weight ofthe tubing string 12 is applied to the BHA), or fluid pressure can beapplied to the annulus 28 and/or an interior of the tubing string asdescribed more fully below. In some examples, a combination of weightand fluid pressure may be used to displace the BHA 44 downward to shiftthe downhole valve 40 a to the open configuration.

With the downhole valve 40 a open, the BHA 44 can be displaced furtherdownward, so that the shifting tool 48 is disengaged from the now-opendownhole valve 40 a, and the packer assembly 46 is positioned betweenthe downhole valve 40 a and the previously opened downhole valve 38. Thepacker assembly 46 can be set in this position to isolate the opendownhole valve 38 from the wellbore 14 above the packer assembly.

The zone 36 b is then fractured by flowing fluids, slurries, gels,acids, spacers, etc., from the wellbore 14, through the open downholevalve 40 a and into the zone 36 b. After the fracturing operation, thepacker assembly 46 can be unset and the BHA 44 can be displacedlongitudinally upward, so that the shifting tool 48 engages the downholevalve 40 a and closes it.

The steps described above for fracturing the zone 36 b can be repeatedfor each of the remaining zones 36 c-f. These steps can include engagingthe shifting tool 48 with the corresponding downhole valve 40 b-e,opening the downhole valve, disengaging the shifting tool from thedownhole valve, setting the packer assembly 46 below the open downholevalve, fracturing the corresponding zone 36 c-f, and shifting thedownhole valve to its closed configuration.

Note that, although six downhole valves 38, 40 a-e and six zones 36 a-fare depicted in FIG. 2A, any number of downhole valves or zones mayexist in other examples. The downhole valves 38, 40 a-e and zones 36 a-fin some examples may not be “above” or “below” each other as depicted inFIG. 2A (such as, in situations where the wellbore 14 is horizontal orotherwise deviated from vertical), but may instead be more distal orproximal relative to the surface along the wellbore 14.

In the FIG. 2B example, the completion is similar in many respects tothe FIG. 2A completion. However, in the FIG. 2B completion, the tubularstring 34 is positioned in another tubular string in the well (such as,another liner or casing 16). The tubular string 34 in this example couldbe of the type known to those skilled in the art as production tubing,although other types of tubular strings may be used in keeping with thescope of this disclosure.

Fluid communication between an interior of the casing 16 and each of thezones 36 a-f is provided by perforations 50. Thus, when one of thedownhole valves 38, 40 a-e is opened, fluid communication is permittedbetween the interior of the tubular string 34 and a corresponding one ofthe zones 36 a-f via the associated perforations 50.

The bottom hole assembly 44 can be used as described above for the FIG.2A completion to actuate the downhole valves 38, 40 a-e in the FIG. 2Bcompletion, in order to selectively fracture each of the zones 36 a-f,or for other purposes (such as, acidizing or other stimulationoperations, conformance treatments, steam or water flooding, production,etc.). Thus, it will be appreciated that the scope of this disclosure isnot limited to use of the bottomhole assembly 44 in any particularcompletion, for any particular purpose or in any particular welloperation.

Referring additionally now to FIGS. 3A-D, cross-sectional views of anexample of the bottomhole assembly 44 are representatively illustrated.The BHA 44 of FIGS. 3A-D may be used in the well system 10 andcompletions of FIGS. 1-2B, or the BHA 44 may be used with other wellsystems and completions.

In the FIGS. 3A-D example, the BHA 44 includes the packer assembly 46and the shifting tool 48. An upper internally threaded connector 52 isused to connect the BHA 44 in the tubing string 12 in the well system10. In other examples, other or different tools, and differentcombinations of tools, may be included in the BHA 44.

When connected in the tubing string 12, an internal flow passage 54extends longitudinally through the BHA 44 and the tubing string 12. Asdepicted in FIG. 3D, a check valve 56 at a distal end of the BHA 44permits upward flow into the flow passage 54 (in a “reverse” circulationdirection), but prevents downward flow through the flow passage 54 (in a“forward” circulation direction).

Ports 58 permit fluid communication between an interior and an exteriorof the BHA 44 below the check valve 56. Thus, fluid can flow from theexterior of the BHA 44 to the interior flow passage 54 via the ports 58,and upward through the BHA via the check valve 56 in the reversecirculation direction. Forward circulation through the check valve 56 isprevented.

As depicted in FIG. 3A, another port 60 below the upper connector 52permits fluid communication between the interior and exterior of the BHA44. Another check valve 62 positioned below the port 60 prevents flowinto the flow passage 54 below the check valve 62 in a forwardcirculation direction, but permits flow upward through the flow passage54.

In the FIGS. 3A-D example, the packer assembly 46 includes an unloadervalve 64, a packer 66, an anchor 68 and a setting controller 70. Otheror different combinations of components may be used in the packerassembly 46 in other examples.

The unloader valve 64 is initially closed, as depicted in FIG. 3A. Inresponse to a sufficient upwardly directed force applied to the upperconnector 52 via the tubing string 12, the unloader valve 64 opens andthereby permits fluid communication between the interior and exterior ofthe BHA 44 (e.g., between the flow passage 54 and the annulus 28 in thewell system 10).

Note that the unloader valve 64 is positioned longitudinally between thecheck valves 56, 62. In addition, note that each of the check valves 56,62 is positioned longitudinally between the unloader valve 64 and thecorresponding one of the ports 58, 60.

The packer 66 is used to seal off an annulus outwardly surrounding theBHA 44. In the well system 10, the packer 66 when set can seal off theannulus 28 radially between the BHA 44 and the tubular string 34.

The anchor 68 is used to secure the BHA 44 in position. In the wellsystem 10, the anchor 68 when set can secure the BHA 44 againstlongitudinal displacement relative to the tubular string 34.

The setting controller 70 is used in this example to control whether ornot the packer assembly 46 sets in response to manipulation of the BHA44. The setting controller 70 allows the packer assembly 46 to be setevery other time the BHA 44 is reciprocated upward and downward in atubular string (such as the tubular string 34 in the well system 10). Inother examples, the setting controller 70 may allow the packer assembly46 to be set every third reciprocation, two out of three reciprocations,or any other number of times per any number of reciprocations. Thepacker assembly 46 can be unset by applying a sufficient upwardlydirected force at the upper connector 52 (e.g., by picking up on thetubular string 12 at the surface).

In the FIGS. 3A-D example, the shifting tool 48 includes an outwardlyextendable flow restrictor 72, one or more engagement members or keys74, and a bypass valve 76. Other or different combinations of componentsmay be used in the shifting tool 48 in other examples.

The flow restrictor 72 is used to increase a restriction to flow throughthe annulus outwardly surrounding the BHA 44 (e.g., the annulus 28 inthe FIGS. 1-2B examples). Viewed differently, the flow restrictor 72 canincrease fluid friction across the BHA 44, thereby increasing alongitudinal force applied to the BHA due to fluid flow through theannulus external to the BHA.

This longitudinal force can be used to operate a downhole valve (suchas, any of the downhole valves 40 a-e) when the keys 74 are engaged withthe downhole valve. The keys 74 in this example are shaped tocooperatively engage a profile (not shown in FIGS. 3A-D, see FIG. 7) inthe downhole valve, so that the longitudinal force is transmitted fromthe BHA 44 to the downhole valve.

Note that a longitudinal force applied to the BHA 44 is not necessarilyproduced by fluid flow across the BHA. For example, set down weight maybe applied to the BHA 44 by slacking off on the tubing string 12 at thesurface, or tension may be applied to the BHA by picking up on thetubing string 12 at the surface. Pressure may be increased or decreasedin the flow passage 54 and/or annulus 28 to thereby produce a desiredlongitudinal force applied to the BHA 44. Thus, the scope of thisdisclosure is not limited to any particular technique, or combination oftechniques, for producing a desired longitudinal force applied to theBHA 44.

In the FIGS. 3A-D example, the keys 74 have an external profile thatengages an internal profile in a downhole valve. In other examples,other types of engagement members (such as, collets, dogs, grippingmembers, projections, receptacles, etc.) may be used for engaging andoperating the downhole valve.

The bypass valve 76 is initially closed, but is used to selectivelypermit fluid communication between the interior and exterior of the BHA44 (e.g., between the flow passage 54 and the annulus 28 in the wellsystem 10). Thus, the bypass valve 76 is similar in this respect to theunloader valve 64. However, the bypass valve 76 opens in response toapplication of a predetermined pressure differential from the interiorto the exterior of the BHA 44 (e.g., from the flow passage 54 to theannulus 28 in the well system 10).

Note that the bypass valve 76 is positioned longitudinally between thepacker 66 and the check valve 56. In addition, note that the packer 66is positioned longitudinally between the unloader and bypass valves 64,76. Thus, when the unloader and bypass valves 64, 76 are open, pressureacross the packer 66 is equalized.

Initially, when the BHA 44 is conveyed into the well, the unloader andbypass valves 64, 76 are closed, the packer assembly 46 is unset (thepacker 66 and anchor 68 are inwardly retracted), and the flow restrictor72 and keys 74 of the shifting tool 48 are inwardly retracted. In thisconfiguration, the BHA 44 can be conveniently conveyed through thetubular string 34 in the well system 10.

While running in, the check valves 56, 62 permit fluid in the tubularstring 34 below the BHA 44 to flow upward through the BHA. Fluid canalso be reverse or forward circulated through the tubing string 12 andannulus 28 via the port 60.

Referring additionally now to FIGS. 4A-B, more detailed cross-sectionalviews of an unloader valve section of the packer assembly 46 arerepresentatively illustrated. In these views it may be seen that theunloader valve 64 includes an outer generally tubular housing 78reciprocably disposed on an inner generally tubular mandrel 80.

Ports 82, 84 formed through the respective outer housing 78 and innermandrel 80 are initially separated and isolated by seals 86. However,when a sufficient longitudinally upwardly directed force is applied tothe outer housing 78, with the inner mandrel 80 being secured againstlongitudinal displacement (such as, by setting the packer assembly 46 asdescribed more fully below), the outer housing will displace upwardrelative to the inner mandrel 80, thereby aligning the ports 82, 84 andpermitting fluid communication between the interior and exterior of thepacker assembly 46.

A biasing device 88 (such as, a spring) applies an upwardly directedlongitudinal force to the inner mandrel 80 relative to the outer housing78, so that the outer housing is continually biased downward relative tothe inner mandrel. Note that, when the packer assembly 46 is set byapplying a downwardly directed longitudinal force to the packerassembly, the unloader valve 64 will be closed, since the inner mandrel80 is connected to the packer 66 and the downwardly directed settingforce is applied via the outer housing 78.

Referring additionally now to FIGS. 5A-C, more detailed cross-sectionalviews of examples of packer, anchor and setting control sections of thepacker assembly 46 are representatively illustrated. In these views itmay be seen that the packer assembly 46 can be similar to, or the sameas, a conventional resettable compression-set packer of the type wellknown to those skilled in the art, in this case the WeatherfordREELFRAC™ packer mentioned above.

As such, the packer, anchor and setting control sections of the packerassembly 46 are not described in detail herein. However, the scope ofthis disclosure is not limited to use of any particular type of packerassembly in the BHA 44.

As depicted in FIG. 5A, the packer 66 includes multiple annular sealelements 90. The seal elements 90 extend radially outward into sealingcontact with a surface outwardly surrounding the packer 66 (such as, aninterior surface of the tubular string 34 in the well system 10) inresponse to longitudinal compression of the seal elements.

The seal elements 90 are longitudinally compressed by downwardlydisplacing an inner mandrel 94 relative to an outer sleeve 92. The innermandrel 94 is connected to the inner mandrel 80 described above.

As depicted in FIG. 5B, the anchor 68 includes outwardly extendableslips 96. When the inner mandrel 94 displaces downward relative to theslips 96, a frusto-conical wedge surface 98 will eventually contact andradially outwardly bias the slips 96 into gripping engagement with thesurface outwardly surrounding the packer 66 (such as, the interiorsurface of the tubular string 34 in the well system 10).

A set of drag blocks 100 are outwardly biased into sliding contact withthe surface, and are provided with a friction-enhancing surface, so thatthe drag blocks and slips 96 can resist longitudinal displacementrelative to the interior surface. This enables the wedge surface 98 todisplace into engagement with the slips 96 when the slips are not yetgrippingly engaged with the interior surface.

The drag blocks 100 also assist in operation of the setting controller70. In the FIG. 5C example, the setting controller 70 includes a J-slottype ratchet device 102. The ratchet device 102 controls an extent ofrelative longitudinal displacement between the inner mandrel 94 and anouter housing 104 connected to the drag blocks 100.

The ratchet device 102 permits the inner mandrel 94 to displacelongitudinally downward relative to the outer housing 104 sufficientlyfar to outwardly extend the seal elements 90 and the slips 96 (due tocontact between the wedge surface 98 and the slips), and thereby set thepacker assembly 46, in response to every third (or whichever sequence ofsetting relative to not setting is desired) longitudinal reciprocationof the inner mandrel 94 (upward then downward displacement of the innermandrel via the tubing string 12 in the well system 10). On certaindownward displacements of the inner mandrel 94, the packer assembly 46is not set, thus allowing the BHA 44 to be conveyed into the wellwithout setting the packer assembly.

Referring additionally now to FIGS. 6A-C, more detailed cross-sectionalviews of flow restrictor, engagement member and bypass valve sections ofan example of the shifting tool 48 are representatively illustrated. TheFIGS. 6A-C shifting tool 48 may be used with the BHA 44 and well system10 described above, or the shifting tool may be used with other bottomhole assemblies or other well systems.

In FIG. 6A, it may be seen that the flow restrictor 72 includes amulti-component radially expandable resilient ring 106. In one example,the ring 106 can include multiple rings having offset or opposed slotswhich form a tortuous path for fluid flow when the ring is radiallyexpanded.

In the FIG. 6A example, the ring 106 has an internal inclined surface106 a facing an outer sleeve 108, and an internal inclined surface 106 bfacing a similarly shaped housing 110. The outer sleeve 108 has a lowerend complementarily shaped relative to the inclined surface 106 a, sothat longitudinally downward displacement of the outer sleeve 108relative to the ring 106 will cause the ring to expand radially outwardbetween the outer sleeve and the housing 110.

Note that the outer sleeve 108 is connected to the inner mandrel 94 ofthe packer assembly 46. Thus, the outer sleeve 108 is connected to thetubing string 12 in the well system 10 via the inner mandrels 80, 94 andouter housing 78 of the packer assembly 46.

As depicted in FIG. 6B, the keys 74 are biased radially outward bysprings 112. However, the keys 74 are initially retained in a retractedposition by an outer generally tubular retainer 114.

In this example, the retainer 114 is formed on an upper end of an outersleeve 116 of the bypass valve 76, as depicted in FIG. 6C. In otherexamples, the retainer 114 and the outer sleeve 116 may be separatecomponents. The outer sleeve 116 is initially prevented from displacinglongitudinally relative to an inner generally tubular mandrel 118 by ashear member 120 (such as, a shear pin, screw or ring).

A ratchet device 122 (such as, a body lock ring 123 positioned betweenthe outer sleeve 116 and the inner mandrel 118) permits downwarddisplacement of the outer sleeve relative to the inner mandrel after theshear member 120 has sheared, but prevents upward displacement of theouter sleeve relative to the inner mandrel.

Ports 124, 126 formed through the respective outer sleeve 116 and innermandrel 118 are initially separated and isolated by seals 128. However,when a sufficient longitudinally downwardly directed force is applied tothe outer sleeve 116 by increasing pressure applied to the flow passage54, the outer sleeve will displace downward relative to the innermandrel 118, thereby aligning the ports 124, 126 and permitting fluidcommunication between the interior and exterior of the shifting tool 48.

The outer sleeve 116 displaces downward in response to a pressuredifferential from the interior to the exterior of the shifting tool 48.Pressure in the flow passage 54 is communicated to a chamber 130 exposedto an internal annular differential piston area 116 a in the outersleeve 116. Another portion of the outer sleeve 116 functions as aclosure member 116 b that initially blocks flow through the ports 126.

Springs 132 positioned in the chamber 130 bias the keys 74longitudinally upward. After the retainer 114 has displaced downward,thereby releasing the keys 74 to be outwardly extended by the springs112, the keys can again be retracted by displacing the keyslongitudinally downward relative to the sleeve 116 against the biasingforce exerted by the springs 132 (e.g., with the keys engaged with aninternal profile and the inner mandrel 118 being displaced upward withthe tubing string 12 in the well system 10), so that the keys are againreceived in the retainer 114. This allows the keys 74 to be releasedfrom an internal profile downhole by applying a sufficient upwardlydirected force to the inner mandrel 118 (e.g., via the tubing string12).

Referring additionally now to FIG. 7, a cross-sectional view of anexample of a downhole valve 40 is representatively illustrated. The FIG.7 downhole valve 40 may be used for any of the downhole valves 40 a-e inthe well system 10 of FIGS. 1-2B, or it may be used in other wellsystems.

As depicted in FIG. 7, the downhole valve 40 includes an outer generallytubular housing 134 and an inner generally tubular closure member 136(such as, a sleeve). In a closed configuration, the closure member 136blocks fluid communication through ports 138 formed through the outerhousing 134. The closure member 136 is releasably retained in the closedconfiguration by a shear member 140 (such as, a shear pin, screw orring).

Internal profiles 136 a,b enable respective downwardly and upwardlydirected longitudinal forces to be applied to the closure member 136.Slots 136 c formed through the closure member 136 define resilientcollets 136 d having projections 136 e formed thereon for releasableengagement with a recess 134 a formed in the outer housing 134. Thecollets 136 d, projections 136 e and recess 134 a enable the closuremember 136 to be releasably retained in the closed position after theshear member 140 has been sheared.

The keys 74 of the shifting tool 48 (see FIG. 6B) are appropriatelyconfigured to engage the profile 136 a when the shifting tool displacesdownward through the downhole valve 40, so that a downwardly directedlongitudinal force can be transmitted from the shifting tool to theclosure member 136, in order to shift the closure member downward to anopen position in which the ports 138 are open for fluid communicationbetween an interior and an exterior of the downhole valve. The keys 74are also appropriately configured to engage the profile 136 b when theshifting tool displaces upward through the downhole valve 40, so that anupwardly directed longitudinal force can be transmitted from theshifting tool to the closure member 136, in order to shift the closuremember upward to the closed position in which flow through the ports 138is prevented.

The downhole valve 40 can be opened and closed repeatedly using theshifting tool 48. Note that it is not necessary for the shifting tool 48to displace the closure member 136 or engage the profiles 136 a,b everytime the shifting tool 48 displaces through the downhole valve 40. Forexample, when the BHA 44 is initially run into the well, the keys 74 canbe retracted and retained by the retainer 114 (see FIG. 6B), so that thekeys do not engage the profile 136 a as the shifting tool 48 displacesdownward through the downhole valve 40.

Referring additionally now to FIGS. 8-21, cross-sectional views of theBHA 44 in operation in the well system 10 are representativelyillustrated. Collectively, these views depict steps in an example of amethod for operating the downhole valves 40 a-e in the well system 10.However, the scope of this disclosure is not limited to any particularsteps or combination of steps utilizing the BHA 44, and is not limitedto a method performed with the well system 10.

In FIGS. 8-21, only the tubular string 34 (with the downhole valves 40a-e) and the tubing string 12 (with the BHA 44) are depicted for clarityof illustration and description. The steps depicted in FIGS. 8-21 may beperformed with either of the completions illustrated in FIGS. 2A & B, orthey may be performed with other types of completions.

Initially, the downhole valve 38 (see FIG. 1) is opened by applyingincreased pressure to the interior of the tubular string 34. The zone 36a can then be fractured by flowing fluid (e.g., proppant slurries, gels,acids, buffers, spacers, etc.) from surface, through the interior of thetubular string 34, and outward through the open valve 38.

After the initial zone 36 a has been fractured, the tubing string 12with the BHA 44 is conveyed into the tubular string 34 and positionedabove the downhole valve 40 a (longitudinally between the downholevalves 40 a,b) as depicted in FIG. 8. As described above, fluid can flowupwardly through the BHA 44 via the check valves 56, 62, and forward andreverse circulation can be accomplished via the port 60 (see FIGS.3A-D).

When the BHA 44 is initially run into the well, the unloader and bypassvalves 64, 76 are closed, and the seal elements 90, slips 96 and keys 74are in their retracted configurations. The downhole valve 38 is open,and the zone 36 a is fractured. The remaining downhole valves 40 a-e areclosed. The BHA 44 is positioned between the downhole valves 40 a,b asdepicted in FIG. 8.

In FIGS. 9A-C, the packer assembly 46 is set in the tubular string 34between the downhole valves 40 a,b. In this example, the packer assembly46 can be set by alternately displacing the packer assembly upward anddownward (e.g., by raising and lowering the tubing string 12 from thesurface) to operate the J-slot ratchet device 102 of the settingcontroller 70 to a position in which a subsequent downward displacementof packer assembly will cause the slips 96 to extend outwardly and gripthe interior surface of the tubular string 34. Further weight applied tothe packer assembly 46 (such as, by slacking off on the tubing string 12at surface) will cause the seal elements 90 to be longitudinallycompressed, so that they extend outward and sealingly engage theinterior surface of the tubular string 34, thereby sealing off theannulus 28 between the BHA 44 and the tubular string 34.

With the packer assembly 46 set in the tubular string 34, the packerassembly can be tested to ensure its functionality. For example, thepacker assembly 46 can be pressure tested by applying increased pressureto the annulus 28 and/or the flow passage 54 to determine whether theseal elements 90 are effectively sealing off the annulus 28, and whetherthe slips 96 are securing the BHA 44 against longitudinal displacement.

In FIG. 10, increased pressure is applied to the annulus 28, and theunloader valve 64 is opened by raising the tubing string 12, therebydisplacing the outer housing 78 upward relative to the inner mandrel 80and aligning the ports 82, 84. Fluid communication is now permittedbetween the interior and exterior of the packer assembly 46 (between theflow passage 54 and the annulus 28 in the well system 10) longitudinallybetween the check valve 62 and the packer 66.

With the unloader valve 64 open, the increased pressure applied to theannulus 28 is transmitted to the flow passage 54 below the check valve62. A pressure drop may be detected at surface as an indication that theunloader valve 64 is open.

In FIGS. 11A & B, the pressure applied to the annulus 28 and to the flowpassage 54 below the check valve 62 is transmitted to an interior of theshifting tool 48. A pressure differential from the interior to theexterior of the shifting tool 48 (e.g., from the flow passage 54 to theannulus 28 in the well system 10) is increased to a predetermined level,at which point the shear member 120 shears and the outer sleeve 116 isdisplaced downward relative to the inner mandrel 118.

The ports 124, 126 are now aligned and fluid communication is permittedbetween the interior and the exterior of the shifting tool 48 (e.g.,between the flow passage 54 and the annulus 28 in the well system 10).The ratchet device 122 prevents the bypass valve 76 from closing afterit has been opened. Note that pressures in the annulus 28 on oppositesides of the packer 66 are now equalized, since the flow passage 54 isnow in communication with the annulus on opposite sides of the packer.

When the outer sleeve 116 displaces downward, the retainer 114 alsodisplaces downward relative to the keys 74. The keys 74 are now biasedto displace outward by the springs 112, and the keys slidingly contactthe interior surface of the tubular string 34 as depicted in FIGS. 11A &B.

In examples in which the retainer 114 and the outer sleeve 116 areseparate components, the retainer may be displaced downward relative tothe keys 74 prior to the outer sleeve 116 being displaced downward. Apressure differential from the interior to the exterior of the shiftingtool 48 (e.g., from the flow passage 54 to the annulus 28 in the wellsystem 10) can be increased to a predetermined level, at which point ashear member (not shown) releasably securing the retainer 114 can shearto allow the retainer to displace downward, and the pressuredifferential can be further increased to another predetermined level, atwhich point the shear member 120 can shear to allow the outer sleeve 116to displace downward to open the bypass valve 76.

In FIGS. 12A-C, the packer assembly 46 is unset by pulling tension inthe tubing string 12 (e.g., by picking up on the tubing string at thesurface). The seal elements 90 and slips 96 are, thus, retracted anddisengaged from the interior surface of the tubular string 34. Theunloader valve 64 remains open.

In FIGS. 13A & B, the BHA 44 is displaced downwardly in the tubularstring 34 (e.g., by lowering the tubing string 12 at the surface).Eventually, the keys 74 will engage the profile 136 a in the closuremember 136 of the downhole valve 40 a, so that the shifting tool 48cannot displace further downward unless the closure member 136 alsodisplaces with the shifting tool.

Note that the flow restrictor 72 is depicted in FIGS. 13A & B in itsextended configuration, so that a flow area through the annulus 28external to the shifting tool 48 is decreased, thereby creating arestriction 28 a to flow through the annulus 28 at the flow restrictor72. This radial expansion can be due to longitudinal compression of theflow restrictor 72 resulting from downward displacement of the outersleeve 108 as the shifting tool 48 displaces downward after the keys 74have engaged the closure member 136.

In this example, the flow restrictor 72 does not seal against aninterior surface of the closure member 136. Instead, the flow restrictor72 restricts flow through the annulus 28, so that a pressuredifferential can be produced due to such restricted flow through theannulus across the flow restrictor. In other examples, the flowrestrictor 72 could sealingly contact the closure member 136 or anotherportion of the downhole valve 40 a, if desired.

In FIG. 14, a sufficient downwardly directed force has been transmittedto the closure member 136 from the shifting tool keys 74 to shear theshear member 140, thereby permitting the closure member 136 to displacedownward with the shifting tool 48. As depicted in FIG. 14, the closuremember 136 has displaced downward somewhat relative to the outer housing134 after the shear member 140 has been sheared.

If not previously extended outward, the flow restrictor 72 is nowextended radially outward due to the compressive force applied to theshifting tool 48 to shear the shear member 140. In some situations (forexample, if the wellbore 14 is highly deviated or horizontal at thedownhole valve 40 a), the weight of the tubing string 12 may not beenough to overcome friction between the tubing string 12 and the tubularstring 34 in order to downwardly displace the BHA 44, shear the shearmember 140 and then downwardly displace the closure member 136 to itsopen position.

In such situations, a pressure differential can be created across theextended flow restrictor 72 to apply an increased downwardly directedlongitudinal force to the shifting tool 48. Increased pressure appliedabove the BHA 44 can also be used to increase the longitudinal forceapplied downwardly to the BHA.

In FIG. 15, a fluid 142 is flowed downward through the annulus 28 to theBHA 44. Flow of the fluid 142 through the annulus 28 is substantiallyrestricted by the outwardly extended flow restrictor 72, so that apressure differential is created across the flow restrictor in theannulus. This pressure differential from above to below the flowrestrictor 72 produces an increased longitudinally downwardly directedforce applied to the shifting tool 48 and transmitted via the keys 74 tothe closure member 136.

In FIGS. 16A & B, the closure member 136 is displaced downward to itsopen position, so that the ports 138 are now unblocked and fluidcommunication between the interior and exterior of the downhole valve 40a is permitted. Note that a sufficient downwardly directed force appliedto the shifting tool 48 to cause the shear member 140 to shear, and todisplace the closure member 136 to its open position, can be anycombination of tubing string 12 weight applied to the BHA 44, force dueto the pressure differential created across the flow restrictor 72 byflow of the fluid 142 through the annulus 28, and force due to thepressure applied above the BHA 44.

The packer assembly 46 is now positioned below the open downhole valve40 a. With the packer assembly 46 in this position, the tubing string 12can be reciprocated upward and downward in the tubular string 34 toactuate the setting controller 70 to a position in which subsequentdownward displacement of the packer assembly will cause it to be set inthe tubular string below the downhole valve 40 a.

In FIGS. 17A & B, the packer assembly 46 is set in the tubular string 34below the open downhole valve 40 a. The seal elements 90 sealinglyengage the interior surface of the tubular string 34 and the slips 96grippingly engage the interior surface of the tubular string 34. Theunloader valve 64 is closed.

In this configuration, the zone 36 b (see FIGS. 2A & B) can be fracturedby flowing fluid (such as, slurries, gels, breakers, spacers, acids,buffers, conformance agents, etc.) through the annulus 28, and outwardthough the open downhole valve 40 a above the set packer assembly 46.The check valve 62, the seals 86 (see FIG. 4A) and the seal elements 90prevent these fluids from flowing downward past the packer assembly 46via the annulus 28 or flow passage 54.

In FIG. 18, the packer assembly 46 is unset after the fracturingoperation. To unset the packer assembly 46, tension is applied to thepacker assembly by raising the tubing string 12 from surface. Theunloader valve 64 opens, and then the seal elements 90 and the slips 96retract out of engagement with the interior surface of the tubularstring 34. The tension applied to the packer assembly 46 is alsotransmitted to the outer sleeve 108 (see FIG. 15), displacing it upwardrelative to the housing 110, and thereby allowing the flow restrictor 72to retract radially inward.

In FIG. 19, the tubing string 12 has been raised sufficiently far in thetubular string 34 for the shifting tool 48 to again engage the downholevalve 40 a. Specifically, the keys 74 now are engaged with the profile136 b in the closure member 136. Further upward displacement of thetubing string 12 and BHA 44 will cause the closure member 136 to alsodisplace upward to its closed position.

In FIG. 20, the BHA 44 has been raised to a position above the downholevalve 40 a. The closure member 136 has been displaced upward to itsclosed position, so that fluid communication is now prevented betweenthe interior and the exterior of the downhole valve 40 a. The fracturedzone 36 b exterior to the downhole valve 40 a will now be unaffected bypressures and fluids in the tubular string 34 in subsequent operations.

In FIG. 21, the BHA 44 has been raised further in the tubular string 34,so that it is now above the closed downhole valve 40 b. The BHA 44 ispositioned longitudinally between the closed downhole valves 40 b,c (seeFIGS. 2A & B).

The BHA 44 is now in a similar position with respect to the downholevalve 40 b as it was with respect to the downhole valve 40 a as depictedin FIG. 8. The steps depicted in FIGS. 9A-20 can now be repeated for thedownhole valve 40 b and corresponding zone 36 c.

These steps can include opening the downhole valve 40 b by downwardlydisplacing the BHA 44 until the keys 74 engage the sleeve profile 136 a,applying a sufficient downward force to displace the closure member 136to its open position, setting the packer assembly 46 below the opendownhole valve 40 b, fracturing the zone 36 c, unsetting the packerassembly 46, displacing the BHA 44 upward through the downhole valve 40b until the keys 74 engage the sleeve profile 136 b, and displacing theclosure member 136 to its closed position. These steps can be performedfor each of the downhole valves 40 a-e in succession, in order tofracture each of the respective zones 36 b-f in succession.

Referring additionally now to FIG. 22, a representative flowchart isdepicted for an example of a method 150 for operating downhole valves.The method 150 is described below as it may be performed with the wellsystem 10 of FIGS. 1-2B and the BHA 44 of FIGS. 3A-D, but the method maybe performed with other well systems or bottomhole assemblies in keepingwith the scope of this disclosure.

In step 152, the downhole valve 38 is opened and the zone 36 a isfractured. In some examples, the downhole valve 38 may be opened byapplying increased pressure to the tubular string 34. The BHA 44 may ormay not be present in the tubular string 34 when the downhole valve 38is opened or when the zone 36 a is fractured.

In step 154, the BHA 44 is conveyed into the tubular string 34. At thispoint, the BHA 44 may be positioned between the downhole valves 40 a,bas depicted in FIG. 8.

In step 156, the packer assembly 46 is set in the tubular string 34 andis tested. This ensures that the packer assembly 46 is fully functionalprior to subsequent fracturing operations (see FIGS. 9A-C).

In step 158, the unloader valve 64 is opened by picking up on the tubingstring 12 (see FIG. 10). Increased pressure applied to the annulus 28 isthereby transmitted to the bypass valve 76, which opens when thepressure differential from the interior to the exterior of the shiftingtool 48 reaches a predetermined level. Opening of the bypass valve 76also causes the keys 74 to be released from the retainer 114, so thatthe keys are biased by the springs 112 to extend outward (see FIGS. 11A& B). In some examples, releasing of the keys 74 from the retainer 114may be separate from opening of the bypass valve 76.

In step 160, the packer assembly 46 is unset by picking up on the tubingstring 12 at the surface to apply tension to the BHA 44 (see FIGS.12A-C).

In step 162, the shifting tool 48 engages the downhole valve 40 a.Specifically, the keys 74 engage the profile 136 a in the closure member136 (see FIGS. 13A & B).

In step 164, the flow restrictor 72 is activated, so that it reduces aflow area through the annulus 28 and can increasingly restrict flow ofthe fluid 142 across the flow restrictor (see FIG. 14). The flowrestrictor 72 extends outward in response to compression of the shiftingtool 48 after the keys 74 have engaged the profile 136 a, which causesthe outer sleeve 108 to displace downward toward the flow restrictor.

Note that use of the flow restrictor 72 is optional, since in somesituations the weight of the tubing string 12 can be sufficient to applya downwardly directed force to the BHA 44 in order to shift the closuremember 136 downward to its open position.

In step 166, the closure member 136 is shifted to its open position (seeFIG. 15). A downwardly directed force is applied from the BHA 44 to theclosure member 136 via the keys 74 to shear the shear member 140 anddisplace the closure member downward. This downwardly directed force maybe a combination of forces due to the weight of the tubing string 12,flow of the fluid 142 through the annulus 28 past the extended flowrestrictor 72, and pressure applied above the BHA 44.

In step 168, the packer assembly 46 is set in the tubular string 34below the open downhole valve 40 a (see FIGS. 16A-17C).

In step 170, the zone 36 b is fractured by flowing fluids from theinterior of the tubular string 34 and outward through the open downholevalve 40 a.

In step 172, the packer assembly 46 is unset after the fracturingoperation of step 170 (see FIG. 18) by applying an upwardly directedforce to the packer assembly (e.g., by raising the tubing string 12 atthe surface). The unloader valve 64 opens and equalizes pressure acrossthe packer 66 prior to unsetting. The upwardly directed force alsodisplaces the outer sleeve 108 upward, so that the expandable ring 106of the flow restrictor 72 can retract inward.

In step 174, the closure member 136 is displaced to its closed positionas the BHA 44 displaces upwardly through the open downhole valve 40 a.The keys 74 engage the profile 136 b in the closure member 136, so thatthe closure member displaces upward with the shifting tool 48 as the BHAdisplaces upward through the downhole valve 40 a (see FIGS. 19 & 20).

In step 176, the BHA 44 is positioned for operating the next downholevalve 40 b in order to fracture the next zone 36 c. In this example, theBHA 44 is positioned above the downhole valve 40 b (longitudinallybetween the downhole valves 40 b,c, as depicted in FIG. 21).

Steps 162-176 can be repeated for each of the downhole valves 40 a-e insuccession to fracture each of the corresponding zones 36 b-f. However,note that it is not necessary for the downhole valves 40 a-e to beoperated between open and closed configurations in any particular orderto fracture the corresponding zones 36 b-f in any particular order. Inaddition, any number of downhole valves may be operated, and any numberof zones may be fractured or otherwise treated, in keeping with thescope of this disclosure.

Although a fracturing operation for each of the zones 36 a-f isdescribed above, it is not necessary in keeping with the scope of thisdisclosure for any zone or combination of zones to be fractured. Otheroperations may be performed (such as, conformance, injection, water orsteam flooding, production, etc.) in other examples.

It may now be fully appreciated that the above disclosure providessignificant advancements to the art of designing, constructing andutilizing well systems, bottomhole assemblies, shifting tools andassociated methods for operating downhole valves. In examples describedabove, the downhole valves 40 a-e can be conveniently and reliablyoperated to allow for selective fracturing of the zones 36 b-f. Fluidflow can be used in some examples to produce a pressure differentialacross an extendable flow restrictor 72 of a shifting tool 48 to assistin displacing the closure member 136 of a downhole valve 40 a-e. Thedownhole valves 40 a-e can be closed by the shifting tool 48 after therespective fracturing operations, so that the fractured zones 36 b-f can“heal” prior to production operations.

The above disclosure provides to the art a shifting tool 48 for use in asubterranean well. In one example, the shifting tool 48 can include aflow restrictor 72 outwardly extendable in the well from a radiallyretracted position to a radially extended position.

The flow restrictor 72 may comprise a resilient ring 106 that isradially outwardly extendable in response to longitudinal displacementof a sleeve 108 relative to the resilient ring 106.

The flow restrictor 72 may be outwardly extendable in response tocompression of the shifting tool 48. The flow restrictor 72 may beoutwardly extendable in response to a longitudinal force applied to theshifting tool 48. The flow restrictor 72 may be inwardly retractable inresponse to a longitudinal force applied to the shifting tool 48.

The shifting tool 48 may also include at least one outwardly extendablekey 74 configured to engage a downhole profile 136 a,b, a retainer 114that retains the key 74 in an inwardly retracted position, and a piston116 a displaceable in response to a pressure differential between anexterior and an interior of the shifting tool 48. The key 74 ispermitted to extend outward in response to displacement of the piston116 a. The pressure differential may comprise a pressure on the interiorof the shifting tool 48 being greater than a pressure on the exterior ofthe shifting tool 48.

The shifting tool 48 may include a valve 76 that selectively preventsand permits fluid communication between the exterior and the interior ofthe shifting tool 48. The retainer 114, the piston 116 a and a closuremember 136 of the valve 76 may be formed on a sleeve 116 that islongitudinally displaceable relative to a generally tubular innermandrel 118 of the shifting tool 48.

A closure member 116 b of the valve 76 may be displaceable with thepiston 116 a.

The shifting tool 76 can comprise a ratchet device 122 that permitsdisplacement of a closure member 116 b of the valve 76 to an openposition, but prevents displacement of the closure member 116 b from theopen position to a closed position.

The above disclosure also provides to the art a method 150 of operatingat least one downhole valve 40 a-e connected in a tubular string 34 in asubterranean well. In one example, the method 150 can include the stepsof flowing a fluid 142 through a flow restriction 28 a (such as, in theannulus 28 between the BHA 44 and the tubular string 34), therebycreating a pressure differential across the flow restriction 28 a; andshifting a closure member 136 of the downhole valve 40 a-e between openand closed positions, in response to the pressure differential, whilethe fluid 142 flows through the flow restriction 28 a.

The method 150 can include forming the flow restriction 28 a radiallybetween a shifting tool 48 and the downhole valve 40 a-e.

The method 150 can include forming the flow restriction 28 a radiallybetween a shifting tool 48 and the closure member 136.

The method 150 can include engaging a shifting tool 48 with a profile136 a,b formed in the closure member 136.

The shifting tool 48 may be engaged with the closure member profile 136a while the fluid 142 flows through the flow restriction 28 a.

The method 150 can include positioning a shifting tool 48 in thedownhole valve 40 a-e, and displacing a flow restrictor 72 radiallyoutward from the shifting tool 48.

The flow restrictor 72 may displace radially outward in response toaxial compression of the shifting tool 48 downhole. The flow restrictor72 may displace radially inward in response to a longitudinal forceapplied to the shifting tool 48.

The flow restrictor 72 displacing step may include reducing an annularflow area between the shifting tool 48 and the downhole valve 40 a-e.

The flow restrictor 72 may displace radially outward after the shiftingtool 48 is engaged with the closure member 136.

The method 150 may include outwardly extending keys 74 from a shiftingtool 48 downhole, in response to fluid pressure applied to the shiftingtool 48, and then engaging the keys 74 with a profile 136 a,b formed inthe closure member 136.

The closure member 136 shifting step may include shifting the closuremember 136 to the open position. The method 150 may further includesubsequently shifting the closure member 136 to the closed position.

The above disclosure also describes a method 150 of operating at leastone downhole valve 40 a-e connected in a tubular string 34 in asubterranean well, in which the method 150 comprises the steps ofpositioning a shifting tool 48 in the tubular string 34; then outwardlyextending keys 74 from the shifting tool 48, in response to fluidpressure applied to the shifting tool 48; then engaging the keys 74 witha profile 136 a,b formed in a closure member 136 of the downhole valve40 a-e; and then shifting the closure member 136 between open and closedpositions.

The fluid pressure may be applied to an annulus 28 formed between theshifting tool 48 and the downhole valve 40 a-e.

The method 150 may include displacing a flow restrictor 72 radiallyoutward from the shifting tool 48. The flow restrictor 72 may displaceradially outward in response to axial compression of the shifting tool48 downhole. The flow restrictor 72 may displace radially inward inresponse to a longitudinal force applied to the shifting tool 48.

The flow restrictor 72 displacing step may include reducing an annularflow area between the shifting tool 48 and the downhole valve 40 a-e.The flow restrictor 72 may displace radially outward after the keys 74are engaged with the closure member 136.

The closure member 136 shifting step may include flowing a fluid 142through a flow restriction 28 a, thereby creating a pressuredifferential across the flow restriction 28 a. The closure member 136may shift in response to the pressure differential, while the fluid 142flows through the flow restriction 28 a.

The method 150 may include forming the flow restriction 28 a radiallybetween the shifting tool 48 and the downhole valve 40 a-e.

The method 150 may include forming the flow restriction 28 a radiallybetween the shifting tool 48 and the closure member 136.

The shifting tool 48 may be engaged with the closure member profile 136a while the fluid 142 flows through the flow restriction 28 a.

Also described above is a shifting tool 48 that in one example includesat least one outwardly extendable key 74 configured to engage a downholeprofile 136 a,b; a retainer 114 that retains the key 74 in an inwardlyretracted position; and a piston 116 a displaceable in response to apressure differential between an exterior and an interior of theshifting tool 48. The key 74 is permitted to extend outward in responseto displacement of the piston 116 a.

The pressure differential can comprise a pressure on the exterior of theshifting tool 48 being greater than a pressure on the interior of theshifting tool 48. In some examples, the pressure differential cancomprise a pressure on the interior of the shifting tool 48 beinggreater than a pressure on the exterior of the shifting tool 48.

The shifting tool 48 can include a valve 76 that selectively preventsand permits fluid communication between the exterior and the interior ofthe shifting tool 48. The retainer 114, the piston 116 a and a closuremember 116 b of the valve 76 may be formed on a sleeve 116 that islongitudinally displaceable relative to a generally tubular innermandrel 118 of the shifting tool 48. In some examples, the retainer 114,the piston 116 a and the closure member 116 b may be formed on multipleor separate components.

A closure member 116 b of the valve 76 may be displaceable with thepiston 116 a.

The shifting tool 48 may include a ratchet device 122 that permitsdisplacement of a closure member 116 b of the valve 76 to an openposition, but prevents displacement of the closure member 116 b from theopen position to a closed position.

The shifting tool 48 may include an outwardly extendable flow restrictor72. The flow restrictor 72 may be outwardly extendable in response tocompression of the shifting tool 48, or in response to a longitudinalforce applied to the shifting tool 48. The flow restrictor 72 may beinwardly retractable in response to a longitudinal force applied to theshifting tool 48.

Although various examples have been described above, with each examplehaving certain features, it should be understood that it is notnecessary for a particular feature of one example to be used exclusivelywith that example. Instead, any of the features described above and/ordepicted in the drawings can be combined with any of the examples, inaddition to or in substitution for any of the other features of thoseexamples. One example's features are not mutually exclusive to anotherexample's features. Instead, the scope of this disclosure encompassesany combination of any of the features.

Although each example described above includes a certain combination offeatures, it should be understood that it is not necessary for allfeatures of an example to be used. Instead, any of the featuresdescribed above can be used, without any other particular feature orfeatures also being used.

It should be understood that the various embodiments described hereinmay be utilized in various orientations, such as inclined, inverted,horizontal, vertical, etc., and in various configurations, withoutdeparting from the principles of this disclosure. The embodiments aredescribed merely as examples of useful applications of the principles ofthe disclosure, which is not limited to any specific details of theseembodiments.

In the above description of the representative examples, directionalterms (such as “above,” “below,” “upper,” “lower,” etc.) are used forconvenience in referring to the accompanying drawings. However, itshould be clearly understood that the scope of this disclosure is notlimited to any particular directions described herein.

The terms “including,” “includes,” “comprising,” “comprises,” andsimilar terms are used in a non-limiting sense in this specification.For example, if a system, method, apparatus, device, etc., is describedas “including” a certain feature or element, the system, method,apparatus, device, etc., can include that feature or element, and canalso include other features or elements. Similarly, the term “comprises”is considered to mean “comprises, but is not limited to.”

Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments ofthe disclosure, readily appreciate that many modifications, additions,substitutions, deletions, and other changes may be made to the specificembodiments, and such changes are contemplated by the principles of thisdisclosure. For example, structures disclosed as being separately formedcan, in other examples, be integrally formed and vice versa.Accordingly, the foregoing detailed description is to be clearlyunderstood as being given by way of illustration and example only, thespirit and scope of the invention being limited solely by the appendedclaims and their equivalents.

1. A shifting tool for use in a subterranean well, the shifting toolcomprising: a flow restrictor outwardly extendable in the well from aradially retracted position to a radially extended position, in whichthe flow restrictor comprises at least one ring.
 2. The shifting tool ofclaim 1, in which the at least one ring is resilient and is radiallyoutwardly extendable in response to longitudinal displacement of asleeve relative to the resilient ring.
 3. The shifting tool of claim 1,in which the flow restrictor is outwardly extendable in response tocompression of the shifting tool.
 4. The shifting tool of claim 1, inwhich the flow restrictor is outwardly extendable in response to alongitudinal force applied to the shifting tool.
 5. The shifting tool ofclaim 1, in which the flow restrictor is inwardly retractable inresponse to a longitudinal force applied to the shifting tool.
 6. Theshifting tool of claim 1, further comprising: at least one outwardlyextendable key configured to engage a downhole profile; a retainer thatretains the key in an inwardly retracted position; and a pistondisplaceable in response to a pressure differential between an exteriorand an interior of the shifting tool, the key being permitted to extendoutward in response to displacement of the piston.
 7. The shifting toolof claim 6, in which the pressure differential comprises a pressure onthe interior of the shifting tool being greater than a pressure on theexterior of the shifting tool.
 8. The shifting tool of claim 6, furthercomprising a valve that selectively prevents and permits fluidcommunication between the exterior and the interior of the shiftingtool.
 9. The shifting tool of claim 8, in which the retainer, the pistonand a closure member of the valve are formed on a sleeve that islongitudinally displaceable relative to a generally tubular innermandrel of the shifting tool.
 10. The shifting tool of claim 8, in whicha closure member of the valve is displaceable with the piston.
 11. Theshifting tool of claim 8, further comprising a ratchet device thatpermits displacement of a closure member of the valve to an openposition, but prevents displacement of the closure member from the openposition to a closed position. 12-23. (canceled)
 24. A method ofoperating at least one downhole valve connected in a tubular string in asubterranean well, the method comprising: positioning a shifting tool inthe tubular string; then outwardly extending keys from the shiftingtool, in response to fluid pressure applied to the shifting tool; thenengaging the keys with a profile formed in a closure member of thedownhole valve; and then shifting the closure member between open andclosed positions.
 25. The method of claim 24, in which the fluidpressure is applied to an annulus formed between the shifting tool andthe downhole valve.
 26. The method of claim 24, further comprisingdisplacing a flow restrictor radially outward from the shifting tool.27. The method of claim 26, in which the flow restrictor displacesradially outward in response to axial compression of the shifting tooldownhole.
 28. The method of claim 26, in which the flow restrictordisplacing comprises reducing an annular flow area between the shiftingtool and the downhole valve.
 29. The method of claim 26, in which theflow restrictor displaces radially outward after the keys are engagedwith the closure member.
 30. The method of claim 26, further comprisingdisplacing the flow restrictor radially inward after the flow restrictoris displaced radially outward.
 31. The method of claim 24, in which theclosure member shifting comprises flowing a fluid through a flowrestriction, thereby creating a pressure differential across the flowrestriction.
 32. The method of claim 31, in which the closure membershifts in response to the pressure differential, while the fluid flowsthrough the flow restriction.
 33. The method of claim 31, furthercomprising forming the flow restriction radially between the shiftingtool and the downhole valve.
 34. The method of claim 31, furthercomprising forming the flow restriction radially between the shiftingtool and the closure member.
 35. The method of claim 31, in which theshifting tool is engaged with the closure member profile while the fluidflows through the flow restriction.
 36. The method of claim 24, in whichthe closure member shifting comprises shifting the closure member to theopen position, and in which the method further comprises then shiftingthe closure member to the closed position.
 37. A shifting tool for usein a subterranean well, the shifting tool comprising: at least oneoutwardly extendable key configured to engage a downhole profile; aretainer that retains the key in an inwardly retracted position; and apiston displaceable in response to a pressure differential between anexterior and an interior of the shifting tool, the key being permittedto extend outward in response to displacement of the piston.
 38. Theshifting tool of claim 37, in which the pressure differential comprisesa pressure on the interior of the shifting tool being greater than apressure on the exterior of the shifting tool.
 39. The shifting tool ofclaim 37, further comprising a valve that selectively prevents andpermits fluid communication between the exterior and the interior of theshifting tool.
 40. The shifting tool of claim 39, in which the retainer,the piston and a closure member of the valve are formed on a sleeve thatis longitudinally displaceable relative to a generally tubular innermandrel of the shifting tool.
 41. The shifting tool of claim 39, inwhich a closure member of the valve is displaceable with the piston. 42.The shifting tool of claim 39, further comprising a ratchet device thatpermits displacement of a closure member of the valve to an openposition, but prevents displacement of the closure member from the openposition to a closed position.
 43. The shifting tool of claim 37,further comprising an outwardly extendable flow restrictor.
 44. Theshifting tool of claim 43, in which the flow restrictor is outwardlyextendable in response to compression of the shifting tool.
 45. Theshifting tool of claim 43, in which the flow restrictor is outwardlyextendable in response to a longitudinal force applied to the shiftingtool.
 46. The shifting tool of claim 43, in which the flow restrictor isinwardly retractable in response to a longitudinal force applied to theshifting tool.